System and method for spinal reconstruction

ABSTRACT

A novel system and method for use for ensuring appropriate positioning of a cable about bone portions, particularly, vertebral bone, for stabilization of the spine during spinal reconstructive and fusion procedures is disclosed. The system includes cabling uniquely adapted for spinal reconstruction processes, ligature passers and hook passers of varying sizes to facilitate looping of the cable about the spinal/vertebral bone, and a tensioning apparatus which secures the cable at a predetermined tensioned value about the vertebral bone. A novel method for applying a cable about vertebral bone for spinal stabilization is also disclosed.

BACKGROUND

[0001] 1. Field of the Disclosure

[0002] The present invention is directed to orthopaedic reconstruction,and more particularly, to a system and method for spinal reconstructionand stabilization of the cervical, lumbar and thoracic spine.

[0003] 2. Discussion of the Prior Art

[0004] Surgical apparatii intended for reconstructive spine surgery andreconstructive spinal procedures in conjunction with bone fusion areknown. These apparatii may typically include metal cables and wireswhich are looped to encircle adjacent bones to hold them together forhealing or fusion. The wires may be clamped together to ensure the cableis retained in a looped tensioned condition about the bone portions.Tensioning apparatii are often used to apply a predetermined tension tothe cable.

[0005] Known cable systems are subject to several disadvantages whichdetract from their usefulness in spinal reconstruction surgery. Inparticular, there are significant complications with the use of metalwires and cables, including breakage of the wire and cable, difficultyin maneuvering about the operative site, cutting into the bone andinterference with imaging procedures. The known tensioning apparatii arecomplicated and difficult to manipulate. Moreover, known systems fail toadequately facilitate the cable looping and securing process, and aredeficient in securing a bone graft utilized in the fusion/healingprocess.

SUMMARY OF THE INVENTION

[0006] Accordingly, the present invention is directed to a novel systemand method for use for ensuring appropriate positioning of a cable aboutbone portions, particularly, vertebral bone, for stabilization of thespine during spinal reconstructive and fusion procedures. The systemincludes cabling uniquely adapted for spinal reconstruction processes,ligature passers and hook passers of varying sizes to facilitate loopingof the cable about the spinal/vertebral bone, and a tensioning apparatuswhich secures the cable at a predetermined tensioned value about thevertebral bone. A novel method for applying a cable about vertebral bonefor spinal stabilization is also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Preferred embodiments of the disclosure are described in furtherdetail herein with reference to the drawings wherein:

[0008]FIG. 1 is a side plan view of the tensioning apparatus of thesystem for orthopaedic spinal stabilization in accordance with theprinciples of the present disclosure;

[0009]FIG. 2 is a side cross-sectional view of the tensioning apparatusof FIG. 1;

[0010]FIG. 3 is an enlarged isolated view of the ratcheting mechanism ofthe tensioning apparatus;

[0011]FIG. 4 is a top plan view of the apparatus of FIG. 1;

[0012]FIG. 5 is an axial plan view of the control knob of the apparatusillustrating the knob's operating positions;

[0013]FIGS. 6A and 6B are schematic views illustrating release andlocking positions of the apparatus;

[0014]FIG. 7 is a view similar to the view of FIG. 3, illustratingrotation of the control knob corresponding to a release position of theapparatus;

[0015]FIG. 8 is an isolated view of a cable engaging pawl of thetensioning apparatus;

[0016]FIGS. 9 and 10 are top plan views of the tensioning apparatusillustrating the cable engaging pawls in an engaged position anddisengaged position, respectively;

[0017]FIG. 11 is an isolated view of the graduated scale mechanismindicating the degree of tension of the looped cable;

[0018]FIG. 12 is a side plan view of the hook passer of the system;

[0019] FIGS. 13A-13C are views of the ligature passer of the system;

[0020] FIGS. 14-17 are views illustrating the sequence of use of theinstruments of the system in accordance with a preferred procedure forspinal stabilization;

[0021]FIG. 18 is a top plan view illustrating movement of the pawlengaging mechanism during actuation of the movable grip; and

[0022]FIG. 19 is a view illustrating securement of the looped cable.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0023] Referring now to the drawings wherein like references identifysimilar or like elements throughout the several views, there isillustrated the system for spinal stabilization in accordance with theprinciples of the present disclosure.

[0024] The following discussion will include a description of eachinstrument utilized in performing a spinal procedure followed by adescription of preferred methods for spinal stabilization utilizing theinstrumentation in accordance with the present disclosure.

[0025] In the discussion which follows, the term “proximal”, as istraditional, will refer to the portion of the structure which is closestto the operator, while the term “distal” will refer to the portion whichis furthest from the operator.

[0026] The system for spinal stabilization includes several components,namely, a surgical cable, a tensioning apparatus for applying thesurgical cable about the spinal bone, and hook and ligature passersutilized to facilitate looping of the cable about the bone. Thepreferred surgical strand or cable is a radiolucent cable system knownunder the trademark SecureStrand™ which is available from SurgicalDynamics, Inc. of Norwalk, Conn. This cable is made of braided highstrength radiolucent ultra-high molecular weight polyethylene (UHMWPE)fiber. The cable consists of 8 yarns of fiber, each having 120 fibers,and being braided to form a cable about 1 mm in diameter. The cablederives its strength from the unique fibers used to create it. Theseextended-chain polyethylene fibers are characterized by a high degree oforientation with a minimum of chain folding. The SecureStrand™ cablesystem avoids many of the potential complications caused by implantationof metal wires and metal cables, including wire/cable breakage,hemorrhage, contusion, laceration and interference with magneticresonance and x-ray imagery. Furthermore, the cable is sufficientlyflexible for looping about bone tissue and may be secured relative tobone tissue through knotting procedures.

[0027] Referring now to FIG. 1, in conjunction with FIGS. 2-4, tensionerapparatus of the system will be discussed. Tensioning apparatus 100includes a handle 102 and an elongated member 104 extending distallyfrom the handle 102, and defining a longitudinal axis “a”. Handle 102includes frame 106 having a stationary grip and a movable grip 108pivotally mounted within the frame 106 about pivot pin 110. Movable grip108 includes pawl 114 which forms part of the ratchet mechanism fortensioning the cable. Pawl 114 pivots about pivot pin 116 and has a coilspring 118 which biases the pawl 114 distally to a normally engagedposition corresponding to an operative position of the ratchet mechanismas depicted in FIG. 2. Coil spring 118 is connected to handle 102through pin 120.

[0028] An elongated actuating member 122 extends through frame 106 andelongate member 104. Actuating member 122 includes an inner rod 124 andan outer sleeve 126 coaxially mounted about the rod 124. A screw 125received within a corresponding threaded aperture 127 at the distal endof rod 124 engages the distal end of outer sleeve 126 such that theinner rod 124 and outer sleeve 126 move concurrently in the distaldirection. Outer sleeve 126 is adapted for rotational movement relativeto rod 124 and has control knob 128 coaxially mounted to its proximalend through stationary screw 131. Outer sleeve 126 includes ratchetteeth 130 which cooperate with pawl 114 of movable grip 108 to moveouter sleeve 126. Outer sleeve 126 further defines a longitudinal slot132 within the elongate member 104 in which an internal sleeve lockingpin 134 is received (FIG. 2).

[0029] As best depicted in FIG. 5, locking knob 128 is rotatable aboutthe longitudinal axis “a” through at least three positions, namely,“release”, “tension” and “lock” positions, to cause rotational movementof the outer sleeve 126 through three corresponding positions. In the“tension” position, which is depicted in FIG. 2, ratchet teeth 130 ofouter sleeve 126 are engaged with pawl 114, thereby permitting the outersleeve 126 to move upon movement of movable grip 108 to tension thecable. Also in the “tension” position, sleeve locking pin 134 isdisposed in longitudinal slot 132 of the outer sleeve 126 such that thelocking pin 134 traverses the longitudinal slot 132 during axialmovement of outer sleeve. This relationship is shown schematically inFIG. 6A. In the “release” position depicted in the cross-sectional viewof FIG. 7, control knob 128 is rotated in a counter-clockwise direction(FIG. 5) to rotate outer sleeve 126, i.e., outer sleeve 126 is angularlydisplaced whereby ratchet teeth 130 are disengaged from pawl 114 therebypermitting actuating member 122 to move without restriction in eitherthe proximal direction or distal direction. In the “lock” position,control knob 128 is rotated clockwise with respect to FIG. 5, “¼” turnthrough an angular displacement of 90°. In this position, internallocking pin 134 is received within a transverse groove 136 extendingfrom longitudinal slot 132 of outer sleeve 126 thereby preventing theouter sleeve 126 from moving axially as depicted in the schematic viewof FIG. 6B. Thus, in the “lock” position, the instrument is not capableof being used in a tensioning mode of operation.

[0030] With reference again to FIGS. 2 and 3, the pawl mechanism furtherincludes a ratchet lock 138 disposed within frame 106 of handle 102adjacent control knob 128. Ratchet lock 138 moves transversely relativeto the longitudinal axis “a” within slot 140 of frame 106 to releasablyengage/disengage ratchet teeth 130 of actuating member 122. Ratchet lock138 is biased to the engaged position depicted in FIG. 3 by coil spring142. Ratchet lock 138 is adapted to releasably lock outer sleeve 126 ofactuating member 122 subsequent to each incremental movement of theouter sleeve 126 in a proximal or tensioning direction, i.e., theratchet lock 138 is displaced downwardly upon engagement of pawl 114with a crest 130 c of each respective ratchet tooth whereby uponclearance of the crest 130 c the ratchet lock 138 engages the leadingvertical surface 130 v of the tooth. Accordingly, when in the “tension”condition of control knob 128 the pawl mechanism releasablyincrementally locks outer sleeve 126 actuating member 122 whilepreventing distal loosening movement thereof. Ratchet lock 138 alsoprovides an audible signal during each “click” of the ratchet teeth toindicate the progression of the tensioning procedure.

[0031] With reference to FIGS. 2, 4 and 8, apparatus 100 furtherincludes a cable engaging pawl mechanism 144 adjacent its distal end.Cable engaging pawl mechanism 144 includes plate 146 which isoperatively connected to outer sleeve 126 of actuating member 122through screw 148. Plate 146 moves longitudinally upon longitudinalmovement of outer sleeve 126. A pair of cable engaging pawls 150 arepivotally mounted to plate 146 through pivot screws 152 on opposed sidesof elongated member 104. Each cable engaging pawl 150 is movable aboutscrew 152 between a cable engaging position depicted in FIGS. 4, 8 and 9and a cable release position. In the engaging position depicted in FIG.9, the pawls 150 clamp the cable ends “e” against respective verticalsurfaces 154 of plate 146. Each pawl 150 is normally biased to theengaged position through torsional spring 155 which is coaxially mountedabout each screw 152.

[0032] A cable release trigger 156 extending beneath elongate member 104moves the pair of cable engaging pawls 150 between the cable engagingand release positions. More particularly, release trigger 156 includes aU-shaped portion 158 engageable by the index finger of the user andrelease rod 160 which extends to plate 146. Release rod 160 isoperatively connected to a pair of cam pins 162 which are receivedwithin corresponding slots 164 of plate 146. Each cam pin 162 traversesits respective slot 164 upon longitudinal movement of release trigger156 to open and close cable engaging pawls 150. In particular, upondepressing or proximal movement of release trigger 156, the cam pins 162connected to the release rod 160 move proximally within slots 164 toengage pawl 150 to open the pawls 150 to the position depicted in FIG.10. Release of release trigger 156 permits pawls 150 to return to theirnormal engaged position under the influence of torsion springs 155.

[0033] With reference now to FIGS. 3, 4 and 11, tensioner apparatus 100further includes a graduated spring scale 170 disposed adjacent controlknob 128 to indicate to the user the degree of tension of the cable.Spring scale 170 includes spring 172 and an indicator pin 174 which isoperatively connected to the pin 172. Pin 172 extends through slot 176of indicator panel 178. Spring 172 operatively engages the proximal endof outer sleeve 126 of actuating member 122. When the outer sleeve 122is displaced rearwardly upon movement of tensioning trigger 108, spring172 is compressed accordingly. The degree of compression of spring 172which is directly related to the forces on actuating member 122 throughthe tensioned cable is indicated by the location of scale pin 174relative to the graduated markings on the indicator panel 178. Thispermits the surgeon to readily obtain the level of tension of the cable.

[0034] Referring now to FIG. 9, in conjunction with FIG. 1, tensioningapparatus 100 further includes a distal bull nose 180. Bullnose 180includes opposed cable receiving grooves 182 (phantom) which receiveeach cable end “e” prior to passing through the cable pawl mechanism144. Apparatus 100 also includes a plastic collar 184 having grooves 186which receives the extreme free ends of the cable “c”.

[0035] Referring now to FIG. 12, hook passer 200 of the system will bediscussed. Hook passer 200 is intended to pass the SecureStrand™ cableabout adjacent vertebral bodies. Hook passer 200 includes a hook body202 defining a general semi-circular shape and having an eye loop 204 ata trailing end and a narrowed blunt entry end 206. Eye loop 204 isgenerally elongated and is dimensioned for reception of the looped cableend. During manufacture, eye loop 204 is bent in itself to define anopen hook appearance detailed in the Figure.

[0036] With reference now to FIGS. 13A-C, ligature passer 300 of thesystem will be discussed. Ligature passer 300 is also intended forlooping the cable end with respect to the vertical bodies and includeshandle 302 and elongated portion 304 extending distally from the handle302. Elongated portion 302 includes an arcuate end portion 306 which isbent between an angle ranging about 70°-110° relative to the axis “a” ofthe elongated portion. The extreme distal end of the ligature passerincludes an eye loop 308 dimensioned for reception of the loopedSecureStrand™ cable. The handle 302 includes a knurled portion 308 tofacilitate gripping engagement by the user.

[0037] The use of system 100 for spinal stabilization will now bediscussed. Subsequent to removal of a portion of the vertebrae and/orremoval of an intervertebral disc, the spine is to be stabilized forhealing and fusion. A three foot length of SecureStrand™ cable is cutfrom a cable roll and folded upon itself. With the assistance of hookpasser 200 or ligature passer 300, depending on the preference of thesurgeon, the looped end of the cable “c” may be engaged to respectiveeye loops of the passers, and the passers are manipulated to pass thecable “c” beneath a pair of opposed vertebrae V₁, V₂, i.e., the spinousprocess or adjacent lamina as depicted in FIG. 14.

[0038] Once the looped cable “c” is positioned with respect to thevertebral bone portions V₁, V₂, attention is directed to tying theappropriate knot with the cable “c”. In the preferred procedure, aracking hitch is formed in the looped cable end by inwardly twisting thecable loop upon itself to the orientation depicted in FIG. 15. Inprocedures involving fusion, a bone graft “b” may be placed between thevertebrae. Thereafter, both free ends “e” of the cable “c” are pulledthrough the racking hitch as depicted in FIG. 16. The bone graft “b” isshown in FIG. 16. Both free ends are advanced in order to close theracking hitch against the vertebral bodies V₁, V₂. Thereafter, the freeends of the cable “c” are used to tie a half hitch, as depicted in FIG.17. The half hitch is advanced to abut the racking hitch to secure thebone graft between the adjacent vertebrae V₁, V₂. The half hitch istightened with moderate hand pressure.

[0039] The procedure is continued by applying tension to each of thecable ends. Tensioner apparatus 100 is introduced into the surgicalsite. A first free end “e” of the cable “c” is positioned about the bullnose 180 of the apparatus with the cable receiving groove 182 and thesecond free end “e” is positioned within the opposed groove 182 asdepicted in FIG. 9. With reference to the FIG. 10, the cable releasetrigger is depressed to outwardly displace the cable engaging pawls 150to permit the cable ends “e” to be passed within the openings definedbetween the pawls 150 and the vertical surfaces 154 of plate 146.Thereafter, the extreme ends of the cable “c” are positioned withingrooves 186 of holder 184 as also depicted in FIG. 10. Movable grip 108is actuated to move, through action of the ratchet mechanism, actuatingmember 122, plate 146 and cable engaging pawls 150 proximally asdepicted in FIG. 18 to tighten the cable ends. During actuation, springscale 170 is continually monitored to monitor the desired degree oftension to the cable strands. Once the desired level of tension isachieved, control knob 128 is rotated to the “release” position, and thecontrol knob is pushed forwardly. Then, the control knob is rotated tothe “lock” position. The cable release trigger is depressed to releasethe cable from the pawls and the ends of the cable are removed from theplastic holder. As depicted in FIG. 19, a second half hitch opposite tothe first half hitch is created to form a square knot. A third halfhitch is then formed opposite the second half hitch and advanced to thesquare knot to secure the cable. Thereafter, the free ends of the cableare cut beyond the knob with, e.g., a cauterizer.

[0040] While the above description contains many specifics, thesespecifics should not be construed as limitations on the scope of thedisclosure, but merely as exemplifications of preferred embodimentsthereof. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended hereto. For example,the system and method of application can be utilized in other areas ofthe body including knee, hip elbow etc. . . . to join adjacent boneportions.

What is claimed is:
 1. A method for retaining first and second tissueportions in predetermined opposed relation during healing, comprisingthe steps of: looping a length of cable upon itself to form a closedcable end and a free cable end; encircling at least partially the firstand second tissue portions with the looped cable; tying the free cableend with respect to the closed cable end; applying a predetermined levelof tension to the free cable end with a tensioning instrument to tightenthe looped cable about the first and second tissue portions; andsecuring the looped cable at the predetermined level of tension toretain the first and second tissue portions in desired relation duringhealing.
 2. The method according to claim 1 wherein the step of tyingincludes creating a racking hitch knot with the closed cable end andpassing the free cable end through the racking hitch knot.
 3. The methodaccording to claim 2 wherein the step of tying includes the step ofcreating a half hitch with the two free cable ends subsequent to passingthe free cable ends through the racking hitch knot.
 4. The methodaccording to claim 3 wherein the step of applying includes engaging thefree cable ends with a tensioning apparatus subsequent to the step ofcreating a half hitch.
 5. The method according to claim 4 wherein thestep of securing includes creating a second half hitch with the cableends opposed the first-mentioned half hitch to form a square knot.
 6. Atensioning apparatus for applying a predetermined level of tension to acable looped about tissue portions, which comprises: a handle; anelongated member extending from the handle and defining a longitudinalaxis; first and second cable engaging pawls mounted to the elongatedmember for releasably engaging respective ends of the cable; a movablegrip mounted to the handle; and an actuating member connected to themovable grip and adapted to longitudinally translate upon movement ofthe movable grip, the actuating member operatively connected to thecable engaging pawls whereby movement of the movable grip causescorresponding movement of the cable engaging pawls to tension the cable.7. The tensioning apparatus according to claim 6 further including amanually engageable release member, the release member movable to movethe cable engaging pawls to a disengaged position with respect to thecable ends.
 8. The tensioning apparatus according to claim 7, whereinthe cable engaging pawls are normally biased to an engaged position withrespect to the cable ends.
 9. The tensioning apparatus according toclaim 8, including a ratchet and pawl associated with the movable gripand actuating member for providing incremental movements of theactuating member.
 10. The tensioning apparatus according to claim 9,including a control knob for controlling operation, the control knobbeing movable between three positions corresponding to lock, tension andrelease positions, wherein in the lock position, the actuating member isprevented from axially moving in a tensioning direction, wherein in thetension position, the ratchet and pawl are engaged with the actuatingmember to permit axial movement of the actuating member in thetensioning direction, and wherein, in the release position, the ratchetand pawl are disengaged thereby permitting unrestricted movement of theactuating movement in the tensioning direction and a release direction.11. The tensioning apparatus according to claim 10, including a secondpawl engageable with the ratchet to prevent movement of the actuatingmember in the release direction.